Drain tofu and pat dry with a paper towel. The drier the better. Cut tofu into 1-inch cubes.
Whisk garlic, sriracha, soy sauce, honey or agave and rice vinegar in a bowl and set aside.
Add tofu to a medium bowl and toss with corn starch to coat.
Heat oil in a large pan. When oil is hot but not smoking, add tofu cubes and fry on all sides without disturbing, for about 4 minutes. Add sauce and carefully stir to coat. Cook for a couple more minutes and then serve and sprinkle with sesame seeds if you have on hand.